The broad objective of the proposed research is to answer the following question: why are tactile graphics difficult to understand? People with normal vision can easily recognize line drawings of objects. However, both blind and sighted people find it very difficult to recognize the same drawings when they are presented as tactile images. For blind people, tactile graphics are the only solution for accessing information in visual diagrams and illustrations found in textbooks. Consequently, the results of the proposed research will be used to improve the production of tactile graphics so that they are better understood by blind people. The specific aims of this project are to: 1) explore how the complexity of tactile images affects perception, 2) determine the effects of spatial and temporal integration on perception of tactile images, and 3) investigate how well people can recognize tactile images of objects embedded in backgrounds. The general methodology of the proposed experiments is to present participants with tactile images and to have them draw what they perceive the images to be. Blind individuals will draw tactile images using special paper and a stylus. The experimenters will evaluate the drawings by using a quantitative measure that computes a distance score reflecting the discrepancy between the original image and the participant's drawing. In the first study, participants will feel tactile stimuli of varying complexity, from simple lines in different orientations to complex depictions of objects. The second study will determine the limitations of tactile perceptual integration by limiting either the spatial or temporal window over which participants feel the image. Participants will either view or feel images through apertures of various sizes (spatial window) or they will have a limited amount of time to view or feel the images (temporal window). In the third study, participants will feel tactile images of objects embedded in simple backgrounds. This research will impact several areas of study, including computer vision, human object and scene recognition, and low vision rehabilitation.